Design of frequency modulator and demodulator

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Design of frequency modulator and demodulator

Microwave SSB transceiver implementation The described zero-IF concept should allow the design of simple and efficient SSB transceivers for an arbitrary frequency band.

Similar technical solutions were first tested in PSK packet-radio transceivers operating at 1. In particular, the AF and IF sections are identical in all three transceivers. The RF sections are similar, however the microstrip filters are necessarily different as well as the low-noise and power devices used in each frequency band.

Finally, the same VCXO module is used, with small modifications, in all three transceivers. Therefore the individual modules will be described first. Of course, similar modules for different frequency ranges will be described together.

Finally, an overview of the construction techniques of the individual modules will be given, as well as shielding of the modules and integration of the complete transceivers. VCXO and multipliers Since a relatively narrow frequency range needs to be covered, a VXO followed by multiplier stages is an efficient solution for the local oscillator.

The VXO is built as a varactor-tuned VCXO with a fundamental-resonance crystal, since the frequency-pulling range of overtone crystals is not sufficient for this application. A fundamental-resonance crystal has a lower Q and is less stable than overtone crystals, but for this application the performance is sufficient.

Fundamental resonance crystals can be manufactured for frequencies up to about 25MHz. Therefore the output of the VCXO needs to be multiplied to obtain microwave frequencies.

Frequency multiplication can be obtained by a chain of conventional multipliers including class-C amplifiers and bandpass filters or by a phase-locked loop. Although the PLL requires almost no tuning and is easily reproducible, the PLL solution was discarded for other reasons.

Shielding and power-supply regulation are also critical, making the whole PLL multiplier more complicated than a conventional multiplier chain. The module already supplies the required frequency of MHz for the MHz version of the transceiver.

In the MHz version, the module supplies MHz by using different multiplication factors. The latter frequency is doubled to MHz inside the transmit and receive mixer modules.

In the MHz version, the module supplies MHz and this frequency is further multiplied to MHz in an additional multiplier module. Of course, the values of a few components need to be adjusted according to the exact operating frequency, shown in brackets for MHz and in [] brackets for MHz.

The corresponding component location for the MHz version is shown on Fig. The exact value of L1 depends on the crystal used.


Some parallel-resonance crystals may even require replacing L1 with a capacitor. L2 and L3 have about nH each or 4 turns of 0.

L4 and L5 are self-supporting coils of 4 turns of 1mm copper-enameled wire each, wound on an internal diameter of 4mm. The VCXO module is the only part of the whole transceiver that requires tuning. L2, L3 and the capacitors in parallel with L4, L5, L6, L7, L8 and L9 should simply be tuned for the maximum output at the desired frequencies.

In a multiplier chain, RF signal levels can easily be checked by measuring the DC voltages over the BE junctions of the multiplier transistors. When the multiplier chain is providing the specified output power, L1 and the capacitor in parallel with the MV varactor should be set for the desired frequency coverage of the VCXO.

If standard "computer grade" Unfortunately not all amateurs are allowed to use the international segment around MHz on 13cm. It is a little bit more difficult to find a crystal for The additional multiplier for MHz is built on a double-sided microstrip FR4 board with the dimensions of 20mmXmm as shown on Fig.

The corresponding component location is shown on Fig.In electronics, ring modulation is a signal-processing function, an implementation of frequency mixing, performed by multiplying two signals, where one is typically a sine wave or another simple waveform and the other is the signal to be modulated.

Design of frequency modulator and demodulator

A ring modulator is an electronic device for ring modulation. A ring modulator may be used in music synthesizers and as an effects unit. LVDT Oscillator/Demodulator Design and Build ECE – Senior Design II Team May 2, design was based heavily on the single-frequency microcontroller-based design, and was successfully implemented into the system.

[] Demodulator be preferred to an analog approach, and as such, the demodulator design was chosen to . Updated: 1/ This page is intended to be a reference list of basic specifications for electronic test equipment, especially obsolete models.

I have been collecting this information for about 25 years, starting with a well thumbed Tucker Electronics catalog, and then adding listings from other catalogs, other web sites, and of course eBay listings. I am not a test equipment dealer and in.

Professional-grade audio/video RF modulator for broadband A/V distribution for all NTSC TV system setup. Converts standard composite BNC/RCA video/audio inputs to a user-defined CATV/UHF channel. Circuit Design: FM Demodulation Frequency modulation (FM) is a technique in which the frequency of a transmitted waveform is varied according to the variations in the message wave.

The FM is a very popular technique since . © Texas Instruments Inc, Slide 1 RF Basics, RF for Non-RF Engineers Dag Grini Program Manager, Low Power Wireless Texas Instruments.

FM Demodulation | Circuit Designing